1. Field of the Invention
The present invention relates to a rocking switch unit.
2. Description of the Related Art
Conventionally, a vehicle such as an automobile has an operating device for operating an electronic apparatus including an air-conditioning system, an audio system, and a navigation system. The operating device includes an operating portion that is operated by a passenger. The operating portion has a seesaw switch configured as a rocking switch unit. In the seesaw switch, a rocking switch knob is attached to a rocking fulcrum to be rockable. When a pressing force is applied to one of longitudinal end portions of the rocking switch knob, a tactile switch that is disposed on a rear side of the one end portion in a pressing direction is pressed, while another tactile switch that is disposed on a rear side of the other end portion in the pressing direction is released. Thereby, conductive conditions of the two tactile switches are switched. The tactile switches are disposed in such a manner that switch surfaces are arranged approximately perpendicularly to the pressing direction of the rocking switch knob.
The seesaw switch is required that when the rocking switch knob is pressed by a user, the switch surface of tactile switch is pressed with a high degree of certainty and the user can receive an operation feeling (feeling of a click) from the pressed tactile switch. Thus, the switch surface of the tactile switch is required to be pressed vertically when one of longitudinal end portions of the rocking switch knob is pressed. In the seesaw switch, the rocking switch knob rotates on the rocking fulcrum. Thus, when a distance between the rocking fulcrum and the switch surfaces of the tactile switches increases, the rocking switch knob is difficult to press the switches surfaces vertically. Thus, it is preferred that the rocking fulcrum is provided near the switch surfaces of the tactile switches.
From a viewpoint of operability of the rocking switch knob, it is required that a pressing direction of the rocking switch knob is approximately perpendicular to an operating panel of the operating device. However, when the distance between an operating surface provided at the rocking switch knob and the rocking fulcrum becomes long, the operating surface may be pressed obliquely because the switch knob rotates on the rocking fulcrum. Thereby, the operability of the switch knob is reduced. Thus, it is preferred that the rocking fulcrum is provided near the operating surface of the switch knob.
However, in the seesaw switch that is attached to an operating panel for operating the electronic apparatus installed in the vehicle, a distance between the rocking switch knob and the tactile switches becomes long, for example, due to a design. In the present case, if the rocking fulcrum of the rocking switch knob is provided near the operating surface of the rocking switch knob, the rocking fulcrum is away from the switch surfaces of the tactile switches. In contrast, if the rocking fulcrum is provided near the switch surfaces of the tactile switches, the rocking fulcrum is away from the operating surface of the rocking switch knob. Thus, it is difficult to ensure compatibility of pressing the tactile switches with a high degree of certainty and improving the operability of the rocking switch knob.
In a rocking switch unit according to a first example of the related art, as shown in FIG. 22, a switch knob 2 includes a knob body 20 and switch-pressing portions 210a and 210b that are disposed on longitudinal end portions of the knob body 20. The switch-pressing portions 210a and 210b protrude toward switch surfaces of tactile switches 5a and 5b. In the present case, a rocking fulcrum 420 is located near an operating surface of the switch knob 2. Thus, an operability of the switch knob 2 is ensured.
However, a distance L1 between the rocking fulcrum 420 and ends of the switch-pressing portions 210a and 210b are long. Thus, when the switch knob 2 is pressed, the ends of the switch-pressing portions 210a and 210b rotate on the rocking fulcrum 420 provided at a base section 400A, and thereby, the switch-pressing portions 210a and 210b are difficult to press the switch surfaces of the tactile switches 5a and 5b vertically. Thus, even when the user presses the switch knob 2, the tactile switches 5a and 5b are not pressed vertically, and the user is difficult to receive the operation feeling.
In a rocking switch unit according to a second example of the related art, as shown in FIG. 23, seesaw pins 600a and 600b are disposed between the switch knob 2 and the tactile switches 5a and 5b. When one of rocking end portions 21a and 21b of the switch knob 2 is pressed, rear ends of the rocking end portions 21a and 21b press down corresponding seesaw pins 600a and 600b, and thereby the switch surfaces of the tactile switches 5a and 5b are pressed. A base section 400B has the rocking fulcrum 420 of the switch knob 2 and guide portions 410a and 410b for guiding a movement of the seesaw pins 600a and 600b in the pressing direction. Thus, the seesaw pins 600a and 600b can press the switch surfaces of the tactile switches 5a and 5b vertically.
In the present case, one of lower surfaces of the rocking end portions 21a and 21b that is located at a releasing position is away from an upper surface of the corresponding seesaw pins 600a and 600b, as shown in FIG. 23. For example, when the rocking end portion 21b located at the releasing position is pressed so that the seesaw pin 600b press the tactile switch 5b, the lower end of the rocking end portion 21b hits the upper surface of the seesaw pin 600b and generates an unpleasant hitting noise. In addition, the present seesaw switch requires two seesaw pins 600a and 600b corresponding to the tactile switches 5a and 5b. Thus, the number of components increases and an assembling efficiency is reduced.
JP-10-125179A discloses a rocking switch unit shown in FIG. 24. The rocking switch unit includes a switch knob 2, tactile switches 5a and 5b, a seesaw holder 300C, and a base section 400C. The seesaw holder 300C has switch-pressing portions 310a and 310b at longitudinal end portions thereof. The base section 400C has a first rocking fulcrum 420 and a second rocking fulcrum 430 coaxially arranged in a pressing direction of the switch knob 2. The switch knob 2 is attached to the first rocking fulcrum 420, and the seesaw holder 300C are attached to the second rocking fulcrum 430 that is arranged between the switch knob 2 and the tactile switches 5a and 5b. The switch knob 2 has a knob body 20 and rocking end portions 21a and 21b disposed at longitudinal end portions of the knob body 20. Because the rocking end portions 21a and 21b constantly contact the seesaw holder 300C, a hitting noise is not generated. In addition, the tactile switches 5a and 5b can be pressed even through the switch knob 2 is away from the tactile switches 5a and 5b. 
In the present rocking switch unit, the switch knob 2 rotates on the first rocking fulcrum 420, and the seesaw holder 300C rotates on the second rocking fulcrum 430. Thus, when a distance L2 between the first rocking fulcrum 420 and lower surfaces of the switch-pressing portions 310a and 310b, and a distance L3 between the second rocking fulcrum 430 and the lower surfaces of the switch-pressing portions 310a and 310b increase, the switch-pressing portions 310a and 310b are difficult to press the switch surfaces of the tactile switches 5a and 5b vertically.
JP-2006-40562A discloses a seesaw switch that includes a switch knob, seesaw pins and spring members that are disposed between longitudinal end portions of the switch knob and the seesaw pins. In the present case, a hitting noise is not generated. However, the number of components increases and an assembling efficiency is reduced.